Lubricant deterioration in high speed engines causes the formation of lacquer, sludge, and carbon deposits on the interior surfaces of the engines which accelerates wear and reduces engine efficiency. To reduce the tendency for such deleterious products to deposit on the surfaces of the engine it is known to incorporate in the lubricating oil additives having dispersancy and/or detergency properties.
The continuing search for and the necessity of having available ashless dispersants and/or detergent additives for motor oils is well known. Since the development of the positive crankcase ventilation system (PVC) there is a greater demand for improved additives of such types.
Various products have been developed for the purpose of providing dispersant and/or detergent properties in lubricating oils. Neutral and over-based metallo-organic compounds such as alkaline earth salts of sulfonic acids, and hydrocarbon-P.sub.2 S.sub.5 reaction products were among the first addition agents used for such purpose. Their in-service drawbacks include the formation of undesirable metal-ash thermal decomposition products. Other proposed addition agents were amine salts, amides, imides, and amides of polybutenyl-substituted polycarboxylic acids. Still other proposed additives were combinations of alkaline earth sulfonates and Mannich condensation products of alkyl substituted hydroxy-aromatic compounds, amines having at least one replaceable hydrogen on a nitrogen atom, and aldehydes; alkaline earth salts of such Mannich condensation products have also been proposed.